The present invention relates to an apparatus and method for the stripping of insulation lengthwise from electrical wires and cables on a continuous basis for the recovery of the metal core.
The metal core of insulated electrical cable has a greater reclamation value if the outer insulating cover has been removed. Past practices taught burning the rubber or plastic insulation from the metal core. However, this practice released toxic pollutants into the environment and degraded the reclamation value of the metal core by contaminating the metal. Thus, many patented prior art devices teach machines that assist with or strip the insulation from an electrical cable to increase the reclamation value of the metal core. Most of these machines work in a continuous manner by pulling the cable past a knife or cutting blade by means of input or feeder wheels. The inventor has found that a key element to the efficient and long term operation of these devices is the ability of the feeder wheels of the machines to grab and pull cables in varying states of integrity and cables of different sizes and types.
One prior art device is the subject of U.S. Pat. No. 5,542,327, issued Aug. 6, 1996, to Roger Schultz. This patent teaches a cable stripping device that uses a flat input or drive wheel to pull the cable into the apparatus. The drive wheel has slots that would be difficult to clean after being filled with pulling lubricant that typically exists on older reclaimed cable. In addition, this patent teaches a device with a single input or drive wheel of a single diameter. As such the cable rate of travel will be the same for cables with large cross-sectional diameters as for cables with small diameters, making this machine a tedious means to reclaim cables with small diameters. Further the apparatus requires multiple positioning wheels of different sizes that must be interchanged to accommodate cables of different sizes. This is cumbersome and time consuming.
U.S. Pat. No. 5,107,735, issued Apr. 18, 1992, to John and Michael Ramun, teaches in-feed and exit drive rollers with cable guides made up of shallow, rounded concave grooves. These shallow, rounded gable guide grooves are likely to be subject to a rapid build-up of pulling lubricant found on the cables that will interfere with the ability of the machine to pull the cable. Similarly, U.S. Pat. No. 4,339,967 issued Jul. 20, 1982, to William B Greenberg, employs drive rollers with shallow grooves that are longitudinally corrugated that will also likely be subject to the rapid build-up of puling lubricant.
A number of other patents teach machines that strip the insulation from a cable, including: U.S. Pat. No. 3,817,132 issued Jun. 18, 1974, to Emery Manning et al., and U.S. Pat. No. 4,339,967 issued Jul. 20, 1982. These machines appear to be overly complicated devices utilizing complex mechanisms for feeding and cutting insulation from the cable metal core.
Many of the prior art wire stripping machines taught in the literature are relatively large and complicated machines that do not appear to be easily transported to a job site or stored out of the way. Further devices have only a single drive wheel, or multiple drive wheels all of a similar diameter, thus they have a single rate of speed for processing small and large cables alike, unless they use stepped motors or multiple speed transmissions. The prior art wire stripping machines also employ drive or input wheels with cable contact surfaces that will be subject to the build-up of cable pulling lubricants that will interfere with the operation of the device.